46 dyes, pigments and colorants used in the textile industry will be tested for their ability to produce mutations in a bacterial test system. These dyes have been selected primarily for two reasons: they are probably the most extensively used in the textile industry and they have not (with three exceptions) been evaluated for their carcinogenicity. In addition 22 of these colorants belong to classes of chemicals that contain particular chemical species known to be carcinogenic. The Ames Salmonella typhimuriam microsomal auxotrophic reversion test for mutagenicity will be used in the assay. Good correlation of mutagenicity in this test with carcinogenicity in animal studies has been demonstrated by a number of independent investigators.